Virtualbox 5.0 installation on Debian 8

Source: https://www.virtualbox.org/wiki/Linux_Downloads

1. Add the "contrib" component to /etc/apt/sources.list, for example:
    # Debian 8 "Jessie"
    deb http://httpredir.debian.org/debian/ jessie main contrib
 
I'm a Windows user and i find gedit as the easiest note editor for gnu/linux like Windows Notepad.
     root@T5500:/home/ariel# apt-get install gedit
     root@T5500:/home/ariel# gedit /etc/apt/sources.list

2. The gedit window pops up and added the line below on the bottom, save and exit.
    deb http://httpredir.debian.org/debian/ jessie main contrib 

3. Update the list of available packages:
    # apt-get update

4. Combine downloading and registering:
    root@T5500:/home/ariel/Downloads#  wget -q https://www.virtualbox.org/download/oracle_vbox.asc -O- | sudo apt-key add
 
5. run the installation:
root@T5500:/home/ariel/Downloads# apt-get install virtualbox-5.0